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The Strait
ofTiran lies at the mouth of the Gulf of Aqaba and is bounded on the west by
the coast of Sinai and on the east by the island ofTiran. In the middle of this
channel are four coral reefs lying in a northeast-southwest direction that
were named after
the I9th-century English cartographers who drew the first
nautical map of this region: Jackson
Reef, Woodhouse Reef, Thomas Reef and Gordon Reef.
These reefs
divide the strait into two canals: to the east is the so-called Grafton
Passage, which is used exclusively by ships going northwards, while to the west
is the Enterprise Passage for ships heading south. East of the island of Tiran
and the nearby island of Sanafir - both part of Saudi Arabia but granted • to
Egypt for military defence - the configuration of the canal floor makes
navigation impossible.
On a level
with the Strait ofTiran, the Gulf of Aqaba is reduced from an average width of
10-12 miles to 2.4 miles, while the seabed ranges from a depth of 1,270 meters
to 250 meters in Enterprise Passage and a mere 71 meters in Grafton Passage. On
the one hand this particular configuration of the strait reduces deep water exchange between the Gulf of Aqaba
and the rest of the Red Sea, causing an increase of salinity and temperature;
on the other it gives rise to an increase in the speed of the tidal currents
and the average height of the waves moved by the wind which, channelled, as it
is, by the tall mountains of Sinai and Saudi Arabia, is in turn subject to
acceleration,
The peculiar topographical arrangement of these reefs. and
the presence of prevailing winds coming from the north, which are stronger in
the morning and calmer in the afternoon, means their western and northern sides
(known as the'outside') are much more exposed to the action of the waves than
the eastern and southern ones, which are 'inside' and sheltered. The strong currents characterizing
the Strait of Tiran transport great quantities of plankton and other nutrient
material every day, thus supplying a great deal of food to the corals and hence
to the reef fish, which in turn are eaten by the large pelagic predators such
as -barracuda, jackfish, tuna and above all sharks, which are always present in
this zone. Consequently, scuba divers in the waters ofTiran are sure to see not
only an infinite number of corals but also rich fauna, both reef and pelagic. However,
they must always be careful of the wind, tides and currents here, which ;will
condition the time, place and type of dive.
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